Display IFC schema in file selector right hand side panel (#1978)

* Display IFC schema in file selector right hand side panel

* Formatting

* Fix possible error when the file name or description contains the word "schema"

src/blenderbim/blenderbim/bim/operator.py

@@ -22,6 +22,7 @@ import json
 import webbrowser
 import ifcopenshell
 import blenderbim.bim.handler
+from pathlib import Path
 from . import schema
 from blenderbim.bim.ifc import IfcStore
 from mathutils import Vector, Matrix, Euler
@@ -46,8 +47,13 @@ class SelectIfcFile(bpy.types.Operator):
     filepath: bpy.props.StringProperty(subtype="FILE_PATH")
     filter_glob: bpy.props.StringProperty(default="*.ifc;*.ifczip;*.ifcxml", options={"HIDDEN"})
 
+    def is_existing_ifc_file(self, filepath=None):
+        if filepath is None:
+            filepath = self.filepath
+        return os.path.exists(filepath) and "ifc" in os.path.splitext(filepath)[1].lower()
+
     def execute(self, context):
-        if os.path.exists(self.filepath) and "ifc" in os.path.splitext(self.filepath)[1]:
+        if self.is_existing_ifc_file():
             context.scene.BIMProperties.ifc_file = self.filepath
         return {"FINISHED"}
 
@@ -55,6 +61,25 @@ class SelectIfcFile(bpy.types.Operator):
         context.window_manager.fileselect_add(self)
         return {"RUNNING_MODAL"}
 
+    def draw(self, context):
+        # Access filepath & Directory https://blender.stackexchange.com/a/207665
+        params  = context.space_data.params
+        # Decode byte string https://stackoverflow.com/a/47737082/
+        directory = Path(params.directory.decode("utf-8"))
+        filepath = os.path.join(directory, params.filename)
+        if self.is_existing_ifc_file(filepath):
+            self.draw_ifc_specs(filepath)
+    
+    def draw_ifc_specs(self, filepath):
+        with open(filepath) as ifc_file:
+            max_lines_to_parse = 50
+            for _ in range(max_lines_to_parse):
+                line = next(ifc_file)
+                if line.startswith("FILE_SCHEMA(('") and line.endswith("'));\n"):
+                    schema = line.split("'")[1]
+                    self.layout.label(text=f"File Schema : {schema}")
+                    break
+
 
 class SelectDataDir(bpy.types.Operator):
     bl_idname = "bim.select_data_dir"